1. Field of the Invention
The present invention relates to a dispensing device for use in, for example, synthesizing an organic material from a trace amount of a sample in organic chemistry or performing PCR (polymerase chain reaction) in biochemistry. More particularly, the present invention relates to a dispensing device, such as μTAS (Micro Total Analysis System), for use in analysis or reaction of a trace amount of a liquid sample.
2. Description of the Related Art
In the field of μTAS for treating a liquid sample, various devices obtained by integrating a plurality of liquid reservoirs for performing analysis or reaction into one and the same device have been heretofore reported.
In order to efficiently introduce a liquid sample into a plurality of liquid reservoirs integrated into one and the same device, a structure shown in FIG. 44 has been reported (see Non-Patent Document 1), in which a plurality of liquid reservoirs 705 parallely-connected between a sample inlet 701 and a sample outlet 703, and a sample introduction channel 707 which is arranged so that all channels between the sample inlet 701 and each of the liquid reservoirs 705 have the same resistance to flow. Each of the liquid reservoirs 705 is connected to the sample outlet 703 through a sample outlet 709. By allowing all the channels between the sample inlet 701 and each of the liquid reservoirs 705 in the sample introduction channel 707 to have the same resistance to flow, it is possible to evenly dispense, into the plurality of liquid reservoirs 705, a liquid sample introduced into the sample introduction channel 707 through the sample inlet 701.
Further, a structure for dispensing a trace amount of liquid capable of quantitatively treating a trace amount of a liquid sample has been also reported (see, for example, Patent Documents 2 and 3). This structure comprises a first channel, a second channel, a third channel which is in communication with the first channel through an opening provided in the channel wall of the first channel, and a fourth channel which is in communication with the second channel through an opening provided in the channel wall of the second channel, connects one end of the third channel to the second channel, and has relatively lower capillary attraction than the third channel. When such a structure for dispensing a trace amount of liquid is used, a liquid introduced into the first channel is drawn into the third channel, and then the liquid remaining in the first channel is removed. As a result, the liquid having a volume corresponding to the capacity of the third channel is dispensed into the second channel.    Patent Document 1: Japanese Patent Application Laid-open No. 2004-163104    Patent Document 2: Japanese Patent Application Laid-open No. 2005-114430    Non Patent Document 1: Masaki Kanai, et al., “A Multi Cellular Diagnostic Device for High-throughput Analysis”, The 8th International Conference on Miniaturized Chemistry and Life Science (μTAS2004), Malmo, Sweden, September 26-30, pp. 126-128, 2004
In the case of the channel configuration described in Non-Patent Document 1 as shown in FIG. 44, a liquid sample remaining in the sample introduction channel 707 provided between the sample inlet 701 and the liquid reservoirs 705 is not used for analysis or reaction performed in the liquid reservoirs 705, and is therefore a so-called dead volume. Particularly, in the case of devices for treating a trace amount of a sample such as μTAS, the capacity of a sample introduction channel is larger than that of a liquid reservoir because the capacity of the liquid reservoir is small. This causes a problem in that the ratio of dead volume of a liquid sample is large.
Further, in the case of a dispensing device having the channel configuration described in Non-Patent Document 1, when the number of liquid reservoirs integrated into the dispensing device is increased, the length of the sample introduction channel needs to be increased, thus resulting in a problem in that the dead volume of a liquid sample is increased.